Trocar system having expandable port

ABSTRACT

An apparatus and method for forming and enlarging percutaneous penetrations comprises an elongate dilation member which receives an elongate expansion member in an axial lumen thereof. The dilation tube includes a tubular braid which usually comprises a mesh of non-elastic filaments which are radially expandable from a small diameter configuration to a large diameter configuration and which is optionally covered by a removable sheath. The dilation tube is percutaneously introduced to a target site within a patient&#39;s body, usually within the abdomen in a laparoscopic procedure. The sheath (if present) is then removed, and the tubular braid thereafter radially expanded by axial insertion of the expansion member through its lumen. The tubular braid is anchored by axial shortening of the mesh and remains in place to permit subsequent exchange of dilation members to provide for different diameter access lumens. Trocar valves may be removably attached to the proximal end of the expansion member to permit the apparatus to be used as a trocar system in laparoscopic procedures where the patient&#39;s abdomen has been insufflated. An anchoring means may optionally be provided at the distal end of the expansion member.

This is a Continuation Division of application Ser. No. 08/026,922 filedMar. 5, 1993 U.S. Pat. No. 5,431,676.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to apparatus and methods forproviding percutaneous access to an internal operative site during asurgical procedure. More particularly, the present invention relates toa trocar system which can be percutaneously introduced while in a narrowdiameter configuration and which after introduction can be radiallyexpanded to accommodate passage of larger diameter surgical instruments.

Minimally invasive surgical procedures rely on obtaining percutaneousaccess to an internal surgical site using small-diameter access tubes(typically 5 to 12 mm), usually referred to as trocars, which penetratethrough the skin and which open to the desired surgical site. A viewingscope is introduced through one such trocar, and the surgeon operatesusing instruments introduced through other appropriately placed trocarswhile viewing the operative site on a video monitor connected to theviewing scope. The surgeon is thus able to perform a wide variety ofsurgical procedures requiring only several 5 to 12 mm punctures at thesurgical site. Patient trauma and recovery time are thus greatlyreduced.

Particular minimally invasive surgical procedures are often referred tobased on the type of scope used to view the region of the body which isthe operative site. Thus, procedures in the abdominal area, which relyon a laparoscope for viewing, are referred to as laparoscopicprocedures. In such laparoscopic procedures, the patient's abdominalregion is typically insufflated (filled with pressured carbon dioxide ornitrogen gas) to raise the abdominal wall and create sufficientoperating space to perform a desired procedure. The trocars used inlaparoscopic procedures must therefore include a valve at their proximalend to allow passage of the scope or surgical instruments whileinhibiting leakage of the insufflating gas. It has also been proposed toperform laparoscopic procedures by mechanically expanding the abdomenrather than using insufflation.

Other minimally invasive surgical procedures include thoracoscopicprocedures performed in the region of the chest, arthroscopic proceduresperformed in body joints, particularly the knee, gynecologicallaparoscopic procedures, and endoscopic surgical procedures performed invarious regions of the body, typically with a flexible scope. Theselatter procedures do not normally employ pressurization and the trocarsused generally do not include pressure valves at their proximal ends.

The design of suitable trocars must fulfill many requirements,particularly for those used in laparoscopic procedures in a pressurizedenvironment. All trocars should be introducible to the patient withminimum trauma and with minimum risk of injury to internal organs. Thetrocars used in laparoscopic procedures should be readily sealable toinhibit the leakage of gas form the abdomen, and in particular should bedesigned to inhibit leakage in the region surrounding the externalperiphery of the trocar which passes through the abdominal wall. It isfurther desirable that trocars have means for anchoring within thepercutaneous passage, and it would be particularly desirable if a singletrocar could accommodate instruments having a wide variety ofcross-sectional shapes and sizes.

Heretofore, trocar designs have met the above listed requirements withmixed results. The accommodation of various sized instruments has beenmet by providing trocars having different fixed diameters. Often, asurgeon will introduce the largest sized trocar, usually 10 to 12 mm,which can then accommodate most or all instruments (which are sizedwithin this maximum) using a rubber adapter. While such an approach isfeasible, the introduction of larger sized trocars exposes the patientto greater trauma and risk of injury than would be the case if smallertrocars were used.

External sealing about the periphery of the trocar has also not beenadequately addressed. Certain trocar designs employ a tapered helicalthread about their periphery. The thread is useful for anchoring, butgreatly enlarges the trocar puncture in order to seal against the lossof pressurized insufflation gas. Other anchors, such as malecotstructures have been employed on the distal end of the trocars, and areeffective for anchoring but provide little sealing against the loss ofpressure.

For these reasons, it would be desirable to provide trocars suitable foruse in laparoscopic and other minimally invasive surgical procedureswhich can be easily introduced to the patient via a relatively smallpuncture (preferably less than 5 mm), which can then be radiallyexpanded (and optionally subsequently reduced) to accommodate a widevariety of instrument sizes, and which provide for improved sealingabout the trocar periphery and anchoring within the target site of theoperative procedure.

2. Description of the Background Art

U.S. Pat. No. 5,183,464, assigned to the assignee of the presentinvention, describes a radially expandable dilator including an elongatedilation tube which receives an elongate expansion tube. European PatentApplication 385 920 describes a variable diameter braid structureintended for capturing and removing stenotic material from bloodvessels. U.S. Pat. No. 5,122,122, describes a trocar sleeve having amalecot structure at its distal end. Trocars for use in laparoscopicprocedures are commercially available from suppliers such as UnitedStates Surgical Corp., Norwalk, Conn.; Endomed division of CooperSurgical, Inc., Shelton, Conn.; and Dexide Inc., Fort Worth, Tex.

U.S. Pat. No. 4,738,666, describes an expandable catheter having anexternal sheath which is perforated to facilitate removal as thecatheter is being expanded. U.S. Pat. No. 4,601,713, describes avariable diameter catheter having an inflatable retention balloon at itsdistal end. The catheter is introduced with an internal stylet whichholds the catheter in a collapsed (reduced diameter) configuration.Removal of the stylet allows the catheter to expand. U.S. Pat. No.4,141,364, describes an expandable endotracheal tube which is insertedin a collapsed configuration and springs back to an expandedconfiguration when air is introduced. Inflatable dilator apparatus aredescribed in U.S. Pat. Nos. 4,589,868 and 2,548,602. Catheters havingexpandable structures are described in U.S. Pat. Nos. 4,986,830;4,955,895; 4,896,669; 4,479,497; and 3,902,492.

U.S. Pat. No. 4,772,266, describes a dilator/sheath assembly that may bepassed over an in-dwelling guide wire in order to enlarge an accesshole, with entry of the sheath further enlarging the hole. U.S. Pat. No.1,213,001, describes a trocar and cannula assembly which includes anintermediate tube to form a three-piece structure. U.S. Pat. No.3,742,958, discloses a cannula having an axial slot to allow the cannulato be stripped from a working catheter which has been introduced throughthe cannula. U.S. Pat. Nos. 4,888,000; 4,865,593; 4,581,025; 3,545,443;and 1,248,492, each describe devices suitable for percutaneouspenetration of a body cavity, blood vessel, or solid tissue. Thedisclosures of each of the U.S. Patents cited in this paragraph arehereby incorporated herein by reference.

U.S. Pat. No. 4,899,729, describes an expansible cannula which includesa coiled conical sheath which can be percutaneously introduced andthereafter expanded by advancing an internal cylinder. U.S. Pat. No.4,716,901 discloses an expandable trocar (not including a trocar valve)comprising a pair of opposed components having sharpened distal tips andcovered by an elastic sleeve over a proximal portion thereof. U.S. Pat.No. 4,846,791, describes a multi-lumen catheter which includes anelastic outer sleeve and an internal divider which, when inserted,expands the sleeve. See also U.S. Pat. Nos. 668,879; 3,789,852;4,411,655; 4,739,762; 4,798,193; 4,921,479; 4,972,827; 5,116,318; and5,139,511, which were made of record in U.S. Pat. No. 5,183,464,assigned to the assignee of the present invention.

A dilator assembly including a guide member having an anchor at itsdistal end is described in copending application Ser. Nos. 07/616,122and 07/913,129, assigned to the assignee of the present invention, thedisclosures of which are incorporated herein by reference. A peel awaysheath is described in copending application Ser. No. 07/967,602,assigned to the assignee of the present invention, the disclosure ofwhich is incorporated herein by reference.

According to the present invention, improved apparatus and methods forforming and enlarging percutaneous penetrations into target locationswithin a patient's body are provided. The apparatus comprises anelongate dilation member including a radially expandable tubular braidand an elongate expansion member which is received in an axial lumen ofthe elongate dilation member to radially expand the braid and provide anenlarged access lumen therethrough. The elongate dilation member furtherincludes a puncturing means near its distal end, typically being anelongate penetrating element having a sharpened distal tip which isremovably received in and extends distally from the axial lumen of thebraid. The elongate dilation member may thus be percutaneouslyintroduced by puncturing the skin. The penetrating member is thenremoved to permit introduction of the elongate expansion member. Theelongate expansion member includes a fixed-radius tubular element havingan axial lumen which defines the desired access path.

The expanded braid of the elongate dilation member provides both ananchoring function and a sealing function. The tubular braid, which ispreferably in the form of a mesh formed from non-elastic polymeric,stainless steel, or other filaments, shortens as it is radiallyexpanded, causing the braid to tighten or clamp on the tissue with whichit is in contact. Such tightening of the braid, when combined with theradial expansion, prevents separation of the tissue layers, providesexcellent anchoring of the elongate dilation member within thepercutaneous penetration, and enhances the peripheral sealing to inhibitloss of insufflation pressure utilized in laparoscopic procedures. Afurther advantage of the tubular braid in the elongate dilation memberis that it will remain in place as the elongate expansion member iswithdrawn therefrom. Thus, elongate expansion members having differentcross-sectional areas and geometries can be introduced and withdrawninto the lumen of the tubular braid, thus allowing the cross-sectionalarea of the access lumen to be changed as desired. Tissue over theexterior of the braid will be able to stretch or relax, as appropriate,to accommodate such changes in diameter of the braid.

In a preferred aspect of the present invention, the elongate dilationmember further comprises a removable protective sheath formed over thebraid to facilitate the initial percutaneous introduction. After theelongate dilation member is in place, the protective sheath can beremoved, either before, during, or after expansion of the tubular braid.In an exemplary embodiment, the removable sheath is axially split as thetubular braid is radially expanded, and the split portions of the sheathremoved after expansion.

In a second preferred aspect of the present invention, the elongateexpansion member further includes a rod having a tapered distal endremovably received in the axial lumen of the fixed-radius tubularelement. The tapered end extends distally from the tubular element, thusfacilitating introduction of the expansion member through the axiallumen of the tubular braid. The rod can be withdrawn from the tubularelement after it has been introduced through the braid, leaving thelumen of the tubular element available as the desired percutaneousaccess path.

In a further preferred aspect of the present invention, the elongateexpansion member will include means for attaching a trocar valve at itsproximal end. Typically, the trocar valve will be removably attached tothe expansion member, permitting the same trocar valve to be used ondifferent elongate expansion members having different cross-sectionalareas, as they are exchanged during a procedure.

In a further preferred aspect of the present invention, the elongatepenetrating element is a needle having a retractable obturator at itsdistal end. The obturator retracts as the needle is penetrated throughskin, and extends forwardly as soon as the needle enters the patient'sbody, thus helping to protect the patient against accidental injury fromthe needle. The exemplary needle is a Veress needle of a type commonlyused in insufflation devices.

The present invention further provides an improved radially expandabledilator of the type including a radially expandable dilation member andan elongate expansion member which is insertable through an axial lumenof the dilation member. The improvement comprises an expandable dilationmember including a radially expandable tubular braid covered by aremovable sheath. The tubular braid preferably comprises an open meshcomposed of a non-elastic polymeric or metallic filaments, whereby thebraid will shorten as its radius is increased.

The present invention still further provides an improved trocar of thetype having a fixed-radius tubular element and a trocar valve disposedat a proximal end of the tubular element. The improvement comprisesproviding a plurality of tubular elements having different fixeddiameters and interchangeable means at their proximal ends for securinga trocar valve thereto. The trocar further comprises means defining aradially expandable axial lumen for selectively receiving and conformingto particular ones of said plurality of tubular elements, whereby thedefining means may be percutaneously introduced to provide an accesslumen for introducing and interchanging tubular members, with the trocarvalve being selectively attached to the tubular element after it hasbeen introduced. Preferably, the defining means comprises an elongateradially expandable tubular braid having means at its distal end forpuncturing tissue as the braid is percutaneously advanced.

The method according to the present invention comprises penetrating anelongate dilation member through a body surface to a target locationwithin a patient's body. optionally, a cover may be removed from thedilation member to expose a radially expandable tubular braid having anaxial lumen which extends from the body surface to the target location.A first fixed-radius tubular element is then inserted through the lumenof the tubular braid, whereby the tubular braid is expanded to anchoritself within the percutaneous penetration. The tubular element thusprovides an access lumen having an enlarged cross-sectional area.Optionally, the method further comprises removing the first fixed-radiustubular element and inserting a second fixed-radius tubular elementhaving a lumen with a different cross-sectional area than that of thefirst tubular element. In this way, access lumens having a desiredcross-sectional area can be introduced at the same location whilecausing the patient minimum trauma. Tissue abrasion is reduced oreliminated by sliding the second tubular element through the tubularbraid, and there is no need to form new percutaneous penetrations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a first component of a trocar systemconstructed in accordance with the principles of the present invention.The first component includes an elongate dilation member having anelongate penetrating element received in an axial lumen thereof.

FIG. 2 is a detailed, cross-sectional view taken at region 2--2 of FIG.1.

FIG. 3 is a detailed view of the proximal end of the component of FIG.1, shown with portions broken away.

FIG. 4 illustrates a first elongate expansion member constructed inaccordance with the principles of the present invention, which forms asecond component of the trocar system of the present invention.

FIG. 5 is a detailed, cross-sectional view of the distal tip taken atline 5--5 in FIG. 4.

FIG. 6 is similar to FIG. 5, except that a rod having a tapered distalend has been removed from a lumen of the structure, with an expandedanchoring means shown in broken line.

FIG. 7 illustrates a second elongate expansion member, similar to thefirst elongate expansion member of FIG. 4, except that it has a largerdiameter. The expansion member of FIG. 7 is shown with an expandedanchoring member in broken line and with the inner tapered rod removed.

FIG. 8 is an enlarged view of the proximal end of the expansion memberof FIG. 8, shown with portions broken away and with a trocar valvesecured thereto.

FIG. 9 illustrates the use of the elongate expansion member of FIGS. 4or 7 for expanding the elongate dilation tube of FIG. 1 and splittingthe sheath about the braid.

FIG. 10 illustrates the elongate dilation member of FIG. 9, shown afterexpansion and deployment of a distal anchoring means.

FIGS. 11 and 12 illustrate the tubular braid of the elongate dilationmember in the radially non-expanded and radially expandedconfigurations, respectively.

FIG. 12A is a graph illustrating the degree of shortening of the tubularbraid of FIGS. 11 and 12 as a function of radial expansion.

FIGS. 13-20 illustrate use of the trocar system of the present inventionin forming and enlarging a percutaneous penetration.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The present invention is useful for forming and enlarging percutaneouspenetrations into a variety of target locations within a patient's bodyfor a multiplicity of purposes. Such purposes include drainage,intra-organ drug administration, feeding, perfusion, aspiration, and thelike, most usually being the introduction of viewing scopes and surgicalinstruments for use in minimally invasive surgical procedures, such aslaparoscopic procedures, thoracoscopic procedures, arthroscopicprocedures, endoscopic procedures, and the like.

The devices of the present invention are particularly valuable sincethey will create a very small initial penetration, usually being belowabout 5 mm, more usually being below about 4 mm, frequently being belowabout 3.5 mm, and preferably being 3 mm or below. The penetration willbe subsequently enlarged to a desired final size, usually having a finaldiameter in the range from about 5 mm to 15 mm, more usually being fromabout 5 mm to 12 mm, and typically being from about 5 mm to 10 mm. Theenlarged penetration will define an access lumen from the outside of thepatient's body to the desired internal location, and it is a particularadvantage of the present invention that the diameter of the access lumencan be changed as will be described in more detail hereinafter.

The dilation apparatus according to the present invention includes anelongate dilation tube having a distal end, a proximal end, and an axiallumen extending from the distal end to the proximal end. The dilationtube includes an expandable tubular braid which is initially in anelongated, narrow-diameter configuration. The braid may be open, butwill often be laminated or covered with a coating or layer of elastic orplastically deformable material, such as silicone rubber, latex,polyethylene C-flex, or the like. The tubular braid is percutaneouslyintroduced in its narrow-diameter configuration, and thereafter radiallyexpanded using an elongate expansion member, as described in more detailhereinafter. The tubular braid is preferably formed as a mesh ofindividual non-elastic filaments (e.g., composed of polyamide fiber(Kevlar®, DuPont), stainless steel, or the like) so that radialexpansion causes axial shortening of the braid. Such axial shortening asthe braid filaments are radially penetrated into the surrounding tissuehelps anchor the dilation member in place within the patient's tissueand helps seal the exterior of the dilation member against the tissue.Such a firmly anchored and gas-tight seal is a particular advantage inlaparoscopic procedures.

The braid may be of conventional construction, comprising roundfilaments, flat or ribbon filaments, square filaments, or the like.Non-round filaments may advantageously reduce the axial force requiredto provide radial expansion. The filament width or diameter willtypically be from about 0.002 inch to 0.25 inch, usually being fromabout 0.005 to 0.010 inch. Suitable braids may be obtained from avariety of commercial suppliers, such as Bently Harris, Lionville, Pa.;Manville Sealing Components, Denver, Colo.; and 3M Ceramic Materials,St. Paul, Minn. A particularly suitable braid is available under thetradename Exando® PT from Bently-Harris.

The elongate dilation member may optionally further include a removablesheath covering the tubular braid. The sheath is usually composed of alubricous material, such as a thin-walled flexible plastic, such aspolyethylene, tetrafluoroethylene, fluorinated ethylenepropylene, andthe like. The sheath protects the tubular braid during initial insertionof the dilation member, but is removed from the braid after the dilationmember is in place. Preferably, the sheath will be weakened along anaxial line to facilitate splitting of the sheath at some point duringthe procedure. Such removable sheaths will usually be employed only ifthe tubular braid does not itself include an elastic or deformable layersecured to the braid filament material. The construction of suitablesheaths is described in detail in copending application Ser. No.07/702,642, assigned to the assignee of the present invention, the fulldisclosure of which is incorporated herein by reference.

The elongate dilation member will further comprise means at its distalend for puncturing tissue as the dilation member is percutaneouslyadvanced. The puncturing means could be secured, either removably orpermanently, to either the tubular braid, optional protective sheath, orboth. In the exemplary embodiment, however, the puncturing meanscomprises a separate elongate penetrating element which is received inan axial lumen of the tubular braid, while the braid is in its axiallyelongate configuration. The penetrating means includes a sharpeneddistal tip which extends distally beyond the distal end of the tubularbraid and optional cover sheath, thus facilitating penetration of thedilation member through the tissue.

In a particularly preferred embodiment, the penetrating element is aneedle which includes an obturator which is retractably mounted thereinand which extends distally beyond the sharpened distal tip. Theobturator is usually spring-loaded, and will thus automatically retractas the needle is advanced through tissue and encounters significanttissue resistance to puncture. The obturator will, however, extenddistally beyond the sharpened distal tip to protect the patient frominjury after the dilation member has entered the desired targetlocation, such as within the insufflated region of the abdomen during alaparoscopic procedure. Such needles are known as Veress needles and arecommonly employed for insufflation in laparoscopic and other procedures.

The elongate dilation member may further comprise an anchor at itsdistal end to be deployed after penetration but prior to expansion. Theanchor would serve to hold the dilation member in place and to preventseparation of the skin and fascial layers as the expansion member isintroduced through the dilation member. Usually, however, the inherentanchoring capacity of the tubular braid is sufficient by itself to holdthe dilation member in place and prevent tissue separation, so that theanchor will not be necessary.

The elongate expansion member includes a fixed-radius tubular elementhaving a distal end, a proximal end, and an axial lumen extendingtherebetween. The axial lumen will have a cross-sectional area which isgreater than that of the tubular braid in its non-radially expandedconfiguration. Thus, by introducing the expansion member through thelumen of the tubular braid and causing the braid to radially expand, anenlarged access channel will be provided by the lumen of thefixed-radius tubular element. To facilitate introduction of the elongateexpansion member through the axial lumen of the tubular braid, a rodhaving a tapered distal end is preferably provided in the lumen of thetubular element. The tapered end extends distally from the tube and actsto spread apart the tubular braid as the expansion member is advanced.The rod can then be removed from the tube to leave the access lumenunobstructed after the expansion member has been fully advanced throughthe tubular braid. Trocar systems of the present invention willpreferably include at least two elongate expansion members havingdifferent cross-sectional areas so that the same dilation member can beselectively used as a channel to introduce access ports of manydifferent sizes.

The elongate expansion member may optionally include an anchoring meansat or near its distal end. The anchoring means can take a variety offorms, including malecot structures, hooks, inflatable balloons, and thelike, and will serve to hold the expansion member in place at the targetlocation after deployment. To further enhance anchoring, an externalclamp or anchor may further be provided at or near the proximal end ofthe expansion member so that tissue disposed between the anchors, e.g.,the abdominal wall, may be captured therebetween. Anchoring provided bysuch clamping will, of course, be in addition to the inherent anchoringachieved by expansion of the tubular braid, as described above.

Usually, the elongate expansion member will include means at itsproximal end for removably securing a trocar valve. The trocar valve issimilar to conventional trocar valves which are fixedly mounted ontrocars. The valve will include internal structure which permits theintroduction of viewing scopes and/or surgical instruments havingdifferent cross-sectional areas, while sealing about the periphery ofsuch devices to prevent loss of insufflation pressure in laparoscopicprocedures. The valves will also typically include stopcocks whichpermit introduction or venting of insufflation gas, irrigation,aspiration, and the like. Conventional trocar valves are manufactured byvarious suppliers, such as Ethicon, Inc., Somerville, N.J.; UnitedStates Surgical Corporation, Norwalk, Conn.; Dexide, Inc., Fort Worth,Tex.; and others.

The length of the elongate dilation tube will vary depending on theintended usage, but will generally be in the range from about 10 cm to25 cm. The length of dilation tubes intended for laparoscopic procedureswill generally be in the range from about 10 cm to 20 cm, typicallybeing in the range from about 10 cm to 15 cm. The length of dilationtubes used in trocar systems intended for thoracoscopic use willgenerally be shorter, typically having a length in the range from about5 cm to 10 cm. The length of the elongate expansion member, of course,will generally be somewhat greater than that of the elongate dilationmember, thus permitting radial expansion of the entire length of thedilation member.

Referring now to the figures, an exemplary trocar system constructed inaccordance with the principles of the present invention will bedescribed. The three principle components of the trocar system are anelongate dilation member 10, best illustrated in FIGS. 1-3, one or moreelongate expansion members 12 and 14, best illustrated in FIGS. 4-8, anda trocar valve 16, best illustrated in FIG. 8. Each of these components,and the use of these components in the method of the present invention,will now be described in greater detail.

The elongate dilation member 10 comprises a tubular braid 20 having anaxial lumen which extends from a handle 22 located at its proximal endto a ferrule 24 on the needle 40 located at its distal end. The braid 20is attached to the proximal handle 22 in a manner that permits radialexpansion of the braid as the expansion member 12 or 14 is subsequentlyintroduced therethrough, as will be described in greater detailhereinafter. The tubular braid will include discrete braid filaments, asdescribed above, and may further comprise a laminated elastomeric orplastically deformable layer, as described above. A passage 26 is formedin the proximal handle 22 in order to permit passage of the expansionmembers into the axial lumen of the tubular braid 20.

The tubular braid 20 is covered with a removable sheath 30 (in theillustrated embodiment) having a handle 32 at its proximal end. Thesheath 30 extends the entire length of the tubular braid 20 andterminates at its proximal end, generally at the location of ferrule 24,as best illustrated in FIG. 2. The removable sheath 30 may beconstructed as described in copending application Ser. No. 07/967,602,the full disclosure of which has been previously incorporated herein byreference.

A needle 40 having a sharpened distal tip 42 and a proximal handle 44 isinitially received within the axial lumen of tubular braid 20. Theferrule 24 is secured near the sharpened distal tip 42 of the needle 20and includes a forward tapered surface 46 (FIG. 2) which facilitatespenetration of the elongate dilation member 10 through the patient'sskin, fascial tissues, and organ walls. In particular, the ferrule 24acts as a transition from the narrow diameter needle 40 to the slightlylarger diameter removable sheath 30. The tubular braid 20 is receivedwithin an annular lumen which is defined between the outer surface ofthe needle 40 and the inner surface of the sheath 30. Alternatively, thedistal end of the sheath 30 may itself be tapered in order to providethe desired smooth transition. It will thus be possible to eliminate theferrule 24 in certain embodiments of the invention.

The needle 40 is preferably in the form of an insufflation needle havinga protective element at its distal tip 42. As illustrated, theprotective element is an obturator 48 having a blunt end 50 which isreciprocatably received in the axial lumen of the needle 40. Theobturator 48 is spring-loaded so that the blunt end 50 extends distallyfrom the sharpened distal tip 42 of the needle 40 in its shelf or "atrest" configuration. As the needle 42 is pressed firmly against thepatient's skin or other tissue, however, the blunt end 50 will beretracted back into the needle 40 so that the sharpened tip 42 canpenetrate. Usually, the obturator 48 will be hollow and include a port52 at its distal end. By providing a valve assembly 54 at its proximalend, the combination of needle 40 and obturator 48 can be used tointroduce or withdraw fluids, particularly being useful for performingthe initial stages of insufflation.

Insufflation needles which can be modified for use in the presentinvention are available from commercial suppliers, such as Ethicon,Inc., Somerville, N.J., (under the tradename Endopaths Ultra VeressNeedle) and United States Surgical Corporation, Norwalk, Conn.(available under the tradename Auto Sutures® Surgineedle®).

Referring now to FIGS. 4-6, the first elongate expansion member 12 willbe described in detail. The expansion member 12 comprises a fixed-radiustubular element 60 having a distal end 62 and a proximal end 64. Aninner coaxial tube 66 is slidably received within the axial lumen of thefixed-radius tubular element 60, being secured to the tubular elementonly at the distal end 68. A proximal handle 70 includes a distal half70A which is secured to the proximal end of inner coaxial tube 66 and aproximal half 70B which is connected to the proximal end of the tubularelement 60. Thus, the inner coaxial tube to be drawn proximally relativeto the fixed-radius tubular element 60 by drawing the halves 70A and 70Baxially apart (as shown in FIG. 7 with respect to a second embodiment ofthe expansion member). In this way, a malecot structure 72 formed nearthe distal end of the fixed-radius tubular element 60 may be expanded,as illustrated in broken line in FIG. 6.

The first elongate expansion member 12 further includes an internalobturator or rod 74 having a handle 76 at its proximal end and a taperedconical surface 78 at its distal end. The tapered conical surface 78extends distally from the distal end 62 of the fixed-radius tubularelement 60, as best illustrated in FIG. 5. The outer peripheral surfacesof both the fixed-radius tubular element 60 and inner coaxial tube 66are chamfered to form a conical surface 80 which is aligned with thetapered conical surface 78 when the rod 74 is fully inserted within theexpansion member 12. As will be seen hereinafter in connection with FIG.9, the combination of the tapered conical surface 78 and tapered region80 facilitates introduction of the expansion member 12 through thetubular braid 20 of the elongate dilation member 10.

Referring now to FIG. 7, a second elongate expansion member 14 isillustrated. The second expansion member 14 is similar in all respectsto the first expansion member 12, except that the diameter offixed-radius tubular element 60' is larger than that of the tubularelement 60 of the first expandable member 12. The particular diametersof the expansion members are not critical, with exemplary ranges beingset forth above. In the exemplary embodiment, the diameter of the firstelongate expansion member 12 will typically be about 6 mm to 8 mm, toprovide an access lumen of approximately 5 mm. The diameter of thesecond expansion member 14 will be about 12 mm to 14 mm, to provide anaccess lumen of about 10 mm. The use of 5 mm and 10 mm access lumens areconventional in laparoscopic surgery. It is a particular advantage ofthe present invention, however, that a wide variety of access lumendiameters can be provided. Thus, it will be expected that trocar systemsmay include two, three, four, or more expansion members withincrementally different diameters to accommodate virtually any scope orinstrument which might be introduced.

FIG. 7 illustrates the expansion member 14 having the inner rod removedtherefrom. After the inner rod is removed, the two halves 70A' and 70B'of the handle 70' may be drawn axially apart, as illustrated in brokenline, in order to expand the malecot structure 72', as also illustratedin broken line.

Referring now to FIG. 8, the handle 70 of first expansion member 12 (aswell as handle 70' of the second expansion member 14) will beconstructed to removably receive the trocar valve 16. The trocar valve16 will be of conventional construction, except that it will include amounting means at its distal end. As illustrated in FIG. 8, the mountingmeans comprises a male bayonet mount 90 which is detachably receivedwithin a female bayonet receptacle 92 in the proximal half 70B of thehandle 70. In this way, the trocar valve 16 can be mounted on differentexpansion members as they are exchanged within the tubular braid 20 ofdilation member 10. This is a particular advantage since it reduces thecost and complexity associated with maintaining an inventory of trocarshaving dedicated valves on each diameter sheath.

Referring now to FIGS. 9 and 10, insertion of elongate expansion member12 through the elongate dilation member 10 will be described in moredetail. Prior to introducing the expansion member 12, of course, theneedle 40 will have been removed from the axial lumen of tubular braid20 of the dilation member 10. The tapered distal end defined by surfaces78 and 80 is introduced through the passage 26 in handle 22, and thusenters the axial lumen in tubular braid 20. The sheath 30 willoptionally have been split by withdrawal of the needle 40 and passage ofthe ferrule 24 through the sheath. Alternatively, introduction of theexpansion member 12 will axially split the sheath 30, as illustrated inFIG. 9. As can be seen, distal advancement of the dilation member 12causes radial expansion of the tubular braid 20, eventually resulting inthe fully expanded braid as illustrated in FIG. 10 (where the inner rod74 has been removed).

After the expansion member 12 is fully inserted, the (undeployed)malecot structure 22 will extend distally from the distal end of thetubular braid, as illustrated in FIG. 10. The sheath 30 (which will havebeen split by passage of the expansion member therethrough) will then bewithdrawn using handle 32, and the inner rod 74 will be withdrawn usinghandle 76. The halves 70A and 70B of handle 70 will then be drawnaxially apart to deploy the malecot structure 72. The trocar valve 16will then be mounted on the proximal half 70B of the handle 70, and thestructure will be generally as illustrated in FIG. 10. Note that it isthe fixed-radius tubular element 60 which provides the structuralsupport within the expanded tubular braid 20. It is also the axial lumenwithin the fixed-radius tubular element 60 which provides the desiredaccess channel from the trocar valve 16 to the distal end of thestructure.

Referring now to FIGS. 11 and 12, the expansion of tubular braid 20 fromits initial narrow-diameter configuration illustrated in FIG. 11 to itsradially expanded configuration illustrated in FIG. 12 will bedescribed. FIG. 12A illustrates the percentage shortening effect as theexemplary Expando® PT braid is radially expanded from about 0.1 inch to0.45 inch.

Referring now to FIGS. 13-20, use of the exemplary trocar system of thepresent invention for performing a percutaneous penetration will bedescribed. The elongate dilation member 10 is initially positioned at alocation on the patient's skin S where it is desired to form thepenetration. The dilation member 10 is then penetrated through the skinS by advancing the sharpened distal tip 42 of the needle 40 (FIG. 1)through the skin, as illustrated in FIG. 14. In the case of laparoscopicprocedures, as soon as the sharpened tip 42 of the needle 40 penetratesthrough the skin into the abdomen, the blunt end 50 of obturator 48 willautomatically extend to protect the patient's internal organs fromaccidental injury. At this point, the lumen of needle 40 may be used forinsufflation if desired.

After the dilation member 10 has been advanced to its desired location,the needle 40 will be withdrawn using handle 44, leaving the sheath 30(which may have been split by withdrawal of the needle 40 and attachedferrule 24) and the tubular braid therein with handle 22 at its proximalend, as illustrated in FIG. 15.

Elongate expansion member 12 is next introduced through the passage 26in handle 22, thus expanding the tubular braid 20 and splitting thesheath 30 (if not already accomplished), as illustrated in FIG. 16. Thepresence of the sheath 30 and braid 20 facilitates radial expansion ofthe penetration which has been formed through the skin S, as illustratedin FIG. 16.

After the expansion member 12 has been fully inserted through thedilation member 10, the inner coaxial rod 66 will be withdrawn from thefixed-radius tube 60, and the sheath 30 will be withdrawn from over theexpanded tubular braid, as illustrated in FIG. 17. The malecot structure72 will be expanded by drawing halves 70A and 70B axially apart, asillustrated in FIG. 17. Trocar valve 16 may then be secured to theproximal half 70B of handle 70, as illustrated in FIG. 18.

If it is desired to change the diameter of the access channel of theexpansion member, the first expansion member 12 may be withdrawn fromthe tubular braid, as illustrated in FIG. 19. The tubular braid 20 willat least partially collapse, but will still provide an internal lumen topermit introduction of a second expansion member, such as the largerdiameter second expansion member 14. The second expansion member 14 maybe introduced through the handle 22 in a manner analogous tointroduction of the first expansion member 12, except that the sheath 30will no longer be in place. The tubular braid 20, however, is sufficientby itself to permit the passage of the expansion member 14 through thepercutaneous penetration through skin S with minimum trauma to thepatient. It will be appreciated that expansion members having smaller orlarger diameters may be exchanged for the initially present expansionmember in the tubular braid 20. Final placement of second expansionmember 14 is illustrated in FIG. 20, where the malecot structure 72' hasbeen deployed by pulling the handle 70' proximally relative to fixedradius tube 60'.

Although the foregoing invention has been described in some detail byway of illustration and example, for purposes of clarity ofunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A dilation tube comprising:a handle having apassage therethrough; an expandable tube having a distal end, a proximalend, and an axial lumen aligned with the passage in the handle, whereinthe tube is attached at its proximal end to one handle and the tube isexpandable from a narrow diameter configuration to a radially expandedconfiguration along its entire length from the proximal end to thedistal end; and an elastic or plastic layer covering the tube.
 2. Adilation tube as in claim 1, wherein the tube comprises a tubular braid.3. A dilation tube as in claim 2, wherein the tubular braid is a mesh ofindividual non-elastic filaments, wherein radial expansion causes axialshortening of the braid.
 4. A dilation tube as in claim 1, having alength in the range from 5 cm to 25 cm.
 5. A dilation tube as in claim1, wherein the tubular braid is expandable from a lumen diameter of 0.1in. to a lumen diameter of 0.45 in.
 6. A dilation tube as in claim 1,wherein the narrow diameter configuration forms a penetration belowabout 5 mm and the penetration can be enlarged to from about 5 mm to 15mm.
 7. A dilation tube comprising:a tubular element having a proximalend, a distal end, and a lumen therethrough, said element including atubular braid reinforcement layer which at least partly defines atubular wall thereof and wherein said tubular element and lumen areexpandable along their entire length from a narrow diameterconfiguration to a radially expanded configuration; and a handleattached to the proximal end of the tubular element and having a passagetherethrough aligned with the lumen of the tubular element.
 8. Adilation tube as in claim 7, wherein the tubular element furtherincludes an elastic or plastic layer covering the braid reinforcementlayer.
 9. A dilation tube as in claim 8, wherein the tubular braid is amesh of individual non-elastic filaments, wherein radial expansioncauses axial shortening of the braid.
 10. A method for providing apercutaneous access lumen in a patient, said method comprising:providinga radially expandable dilation tube having a needle removably insertedin an axial lumen thereof; penetrating the dilation tube and needlethrough tissue to a target location; withdrawing the needle from thedilation tube to leave the axial lumen available for subsequentintroduction of a member.
 11. A method as in claim 10, wherein thedilation tube comprises a tubular braid.
 12. A method as in claim 10,wherein the dilation tube comprises an expandable tube covered by anelastic or plastic layer.
 13. A method as in claim 12, wherein theexpandable tube comprises a tubular braid.
 14. A method as in claim 12,wherein the expandable tube is covered with an elastic layer, furthercomprising passing an expansion member through the lumen of the dilationtube and withdrawing the expansion member from the lumen, wherein theelastic layer causes at least partial collapse of the expandable tubeafter the expansion member is withdrawn.
 15. A method for percutaneouslypositioning a dilation tube in a patient, said methodcomprising:penetrating the dilation tube through tissue to a targetlocation, wherein the dilation tube is radially expandable; passing amember through an axial lumen of the dilation tube to radially expandthe dilation member from a narrow diameter configuration to a radiallyexpanded configuration; and removing the expansion member, wherein thedilation tube at least partly collapses but continues to provide anaccess lumen for subsequent introduction of another tube therethrough.16. A method as in claim 15, wherein the dilation tube comprises atubular braid.
 17. A method as in claim 15, wherein the dilation tubecomprises an expandable tube covered by an elastic or plastic tube. 18.A method as in claim 17, wherein the expandable tube comprises a tubularbraid.
 19. A method as in claim 15, further comprising introducinganother member through the axial lumen of the dilation tube after thefirst member has been removed.
 20. A dilation tube comprising:a handlehaving a passage therethrough, said passage having a diameter, anexpandable tube having a distal end, a proximal end, and an axial lumenaligned with the passage in the handle, wherein the proximal end of thetube has a diameter substantially equal to the remainder of the tube andwherein the remainder of the tube is expandable from a narrow diameterconfiguration to a radially expanded configuration along its entirelength; and an elastic or plastic layer covering the tube.
 21. Adilation tube as in claim 20, wherein the tube comprises a tubularbraid.
 22. A dilation tube as in claim 21, wherein the tubular braid isa mesh of individual non-elastic filaments, wherein radial expansioncauses axial shortening of the braid.
 23. A dilation tube as in claim20, having a length in the range from 5 cm to 25 cm.
 24. A dilation tubeas in claim 20, wherein the tubular braid is expandable from a lumendiameter of 0.1 in. to a lumen diameter of 0.45 in.
 25. A dilation tubeas in claim 20, wherein the narrow diameter configuration forms apenetration below about 5 mm and the penetration can be enlarged to fromabout 5 mm to 15 mm.